This invention relates to a nut type fastener applicable to a threaded bolt or the like. The purpose is to enable placement of the fastener over a bolt, screw or stud, and to tighten the same onto a workpiece upon a fractional turn thereof. Two types of nut fasteners of this type have been proposed, those which turn to threadedly engage, and those which reciprocate to do so, a characteristic feature thereof being the use of cams.
With regard to the turning or twist type of nut control, there is U.S. Pat. No. 820,941 to Swarthout which discloses the basic concept of having two nut halves and a surrounding cam that forces the two halves together so as to engage a threaded bolt. And there is U.S. Pat. No. 4,083,393 to Okada which discloses a quick insertion concept, but with no quick release. Although split nuts are disclosed, they have full threads with no suggestion of semi threads.
With regard to the reciprocating type of nut control, there is U.S. Pat. No. 2,367,480 to Beswick which discloses segments with full threads with a locking taper nut interior, but with no cone engagement with the workpiece, and with no snap ring for securement. There is U.S. Pat. No. 750,675 to Michelin which discloses an externally threaded collet that draws split threads together, but no cone engagement with the workpiece. There is U.S. Pat. No. 3,352,341 to Schertz which discloses spring separation of splt parts driven by ribs, but no cone engagement with the workpiece. And there is U.S. Pat. No. 4,068,697 to Schiaffino which discloses a tapered collet like nut entering a sleeve, but with no cone engagement with the workpiece.
It is a general object of this invention to provide a manually operable nut that is adapted to be quickly locked on or released from a threaded member to secure a workpiece. As described herein there are two forms of quick lock and release fasteners, both embodying a split nut and cam lock and release principle of operation; a first form operating by manual turning or twisting, and a second form operating by reciprocation or push-pull manipulation. The concept herein disclosed is characterized by a split nut that is cam operated to contract together and cam controlled to separate. The cam is manually operated by turning in the first form, and by reciprocation in the second form. A feature and object of this invention is the fractional turn and/or short reciprocal stroke involved to engage or to loosen the fastener.
It is an object of this invention to provide a split nut for releasable threaded engagement with a bolt or the like, whereby diametral movements are reduced and minimized. To this end the internal nut threads are circumferentially truncated, and referred to herein as semi threads, as will be described and as clearly shown in the drawings.
It is an object of this invention to provide constrictive driving engagement of the split nut with the worpiece, whereby thread engagement and cam operation is ensured. With the present invention nut engagement with the workpiece is by means of cone engagement into a complementary countersink in the workpiece, forcing the split nut halves into thread engagement, and for holding them against rotation for operation in the first form of turning or twist type fastener disclosed herein.
It is an object of this invention to provide for automatic separation of the split nut halves, whereby application of the fastener over a threaded bolt is facilitated. To this end spring means separates the split nut halves, while permitting them to be cammed together over the bolt.
It is an object of this invention to provide positioning means to locate the cam control of the fastener in either the locking mode or the release mode, as may be required. This feature is found in the second form wherein there is a detent means holding said two modes. In practice, a snap ring is carried by a drive plate to ride over the cam shaped exterior of the split nut halves. Additionally, a return spring lifts the drive plate to the release mode, ready for application to a threaded bolt or the like.